The Finisher Transport Assembly (FTA) of a printing system typically employs nip rollers for driving the media sheet (paper) along the process path. Idler nip rollers oppose drive nip rollers for moving, guiding and controlling the paper. A paper jam in the FTA requires opening a large, heavy main cover to clear the jam. The idler nip rollers and shafts are mounted on the transport main cover and are raised up to free the paper as the main cover is lifted. The rollers and shafts and the structure to support them result in significant weight, requiring counter-balancing of the main cover with costly springs and mechanisms. In addition, failure of these counterbalancing systems could result in the main cover slamming down on the user. In some printers, there may not be room to open the entire FTA cover—for example, if the marking engine or scanner is disposed above the FTA. Secure, releasable latching of a large main cover can require an elaborate mechanism with added cost.
Further problems arise in aligning the idler rollers with their drive counterparts. An unfavorable tolerance buildup can occur from the drive rollers, through the base support structure, through the hinge, through the cover structure to the idler rollers. This can cause the idler rollers to be out of alignment with the drive rollers. Uniform nip force is also difficult to maintain. These conditions can result in skew registration error of the paper. Hence, raising the entire main cover requires a design having more locating features and tighter tolerances, incurring increased cost, to ensure proper paper control. Not lifting the idler rollers would make jam removal difficult while the paper is clamped in the nips. On some machines, it becomes necessary to reach deep into the mechanism, grasp a jammed sheet sight unseen, and pull the sheet from the grasp of nip rollers.
Accordingly, it would be desirable to provide an apparatus capable of easy, one-handed access to a paper jam, while releasing the respective nips to aid in freeing the jam.